The Deletion of the Bre1 Gene in Aspergillus nidulans Impairs Mitotic Growth, Meiosis, and DNA Damage Repair

Bre1 is a homotetrameric E3 ubiquitin-protein ligase that heterodimerizes with Rad6, an E2 ubiquitin-conjugating enzyme, in order to ubiquitinate lysine 123 in Aspergillus nidulans. This post-translational modification promotes methylation of lysines 4 and 79 on histone H3, which are required for certain damage repair pathways and for both optimal mitotic cell growth and meiosis [1-3, 12]. ΔBre1 mutants were generated by exposing protoplasts from strains auxotrophic for pyridoxine to a three-way fusion construct made from the Bre1 5’ and 3’ flanking regions and the Aspergillus fumigatus pyroA gene, which served as a selectable marker. Molecular diagnosis was confirmed via trans-locus PCR. Phenotypic analysis indicates that the loss of Bre1 increases sensitivity to DNA damage agents, decreases mitotic cell growth, and inhibits meiosis. The severe developmental defects of ΔBre1 mutants are consistent with the known roles of Bre1 as an upstream regulator of several important cellular functions. [excerpt

Dynamic Response Testing in an Electrically Heated Reactor Test Facility

Non-nuclear testing can be a valuable tool in development of a space nuclear power or propulsion system. In a non-nuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Standard testing allows one to fully assess thermal, heat transfer, and stress related attributes of a given system, but fails to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and full nuclear testing. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response characteristics, and assess potential design improvements at a relatively small fiscal investment. Initial system dynamic response testing was demonstrated on the integrated SAFE-100a heat pipe cooled, electrically heated reactor and heat exchanger hardware, utilizing a one-group solution to the point kinetics equations to simulate the expected neutronic response of the system (Bragg-Sitton, 2005). The current paper applies the same testing methodology to a direct drive gas cooled reactor system, demonstrating the applicability of the testing methodology to any reactor type and demonstrating the variation in system response characteristics in different reactor concepts. In each testing application, core power transients were controlled by a point kinetics model with reactivity feedback based on core average temperature; the neutron generation time and the temperature feedback coefficient are provided as model inputs. Although both system designs utilize a fast spectrum reactor, the method of cooling the reactor differs significantly, leading to a variable system response that can be demonstrated and assessed in a non-nuclear test facility

A Psychosocial Approach to Predicting Self-Harm in Heterogeneous Populations

Previous studies have demonstrated relationships between deliberate self-harm and psychological distress and social functioning (for a review see Nock, 2010). However, few studies have examined psychological distress and social functioning at the same time in order to compare these predictors of deliberate self-harm. Using a more comprehensive, psychosocial approach may allow more accurate predictions of deliberate self-harm. Accurate predictions could aid in the intervention and treatment of individuals who engage in deliberate self-harm, regardless of their population; that is, whether they are seeking treatment for symptoms of Borderline Personality Disorder, or if they are a member of the community. In the current study, we used a sample of individuals with Borderline Personality Disorder (N = 60) and a community sample of undergraduate college students (N = 116), all of whom reported engaging in deliberate self-harm at least once in the past year. Participants completed measures of deliberate self-harm (outcome variable), psychological distress (specifically depression, anxiety, obsessive-compulsion, and interpersonal sensitivity; predictor variables), and social functioning (positive support and negative interactions with family members, friends, and a romantic partner; predictor variables). We found that the population (or sample type) was the strongest predictor of deliberate self-harm, with individuals with Borderline Personality Disorder engaging in more deliberate self-harm than students. Additionally, anxiety predicted deliberate self-harm for individuals with Borderline Personality Disorder. No social functioning variables predicted deliberate self-harm. Explanations for findings and treatment implications are discussed. Keywords: self-harm, distress, social support, Borderline Personality Disorder, student healt

Single Channel Testing for Characterization of the Direct Gas Cooled Reactor and the SAFE‐100 Heat Exchanger

Experiments have been designed to characterize the coolant gas flow in two space reactor concepts that are currently under investigation by NASA Marshall Space Flight Center and Los Alamos National Laboratory: the direct‐drive gas‐cooled reactor (DDG) and the SAFE‐100 heatpipe‐cooled reactor (HPR). For the DDG concept, initial tests have been completed to measure pressure drop versus flow rate for a prototypic core flow channel, with gas exiting to atmospheric pressure conditions. The experimental results of the completed DDG tests presented in this paper validate the predicted results to within a reasonable margin of error. These tests have resulted in a re‐design of the flow annulus to reduce the pressure drop. Subsequent tests will be conducted with the re‐designed flow channel and with the outlet pressure held at 150 psi (1 MPa). Design of a similar test for a nominal flow channel in the HPR heat exchanger (HPR‐HX) has been completed and hardware is currently being assembled for testing this channel at 150 psi. When completed, these test programs will provide the data necessary to validate calculated flow performance for these reactor concepts (pressure drop and film temperature rise). © 2004 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87574/2/741_1.pd

Design of Refractory Metal Life Test Heat Pipe and Calorimeter

Heat pipe life tests have seldom been conducted on a systematic basis. Typically, one or more heat pipes are built and tested for an extended period at a single temperature with simple condenser loading. Results are often reported describing the wall material, working fluid, test temperature, test duration, and occasionally the nature of any failure. Important information such as design details, processing procedures, material assay, power throughput, and radial power density are usually not mentioned. We propose to develop methods to generate carefully controlled data that conclusively establish heat pipe operating life with material-fluid combinations capable of extended operation. The test approach detailed in this Technical Publication will use 16 Mo-44.5%Re alloy/sodium heat pipe units that have an approximate12-in length and 5/8-in diameter. Two specific test series have been identified: (1) Long-term corrosion rates based on ASTM-G-68-80 (G-series) and (2) corrosion trends in a cross-correlation sequence at various temperatures and mass fluences based on a Fisher multifactor design (F-series). Evaluation of the heat pipe hardware will be performed in test chambers purged with an inert purified gas (helium or helium/argon mixture) at low pressure (10-100 torr) to provide thermal coupling between the heat pipe condenser and calorimeter. The final pressure will be selected to minimize the potential for voltage breakdown between the heat pipe and radio frequency (RF) induction coil (RF heating is currently the planned method of powering the heat pipes). The proposed calorimeter is constructed from a copper alloy and relies on a laminar flow water-coolant channel design to absorb and transport energ

Differential Uptake of Gold Nanoparticles by 2 Species of Tadpole, the Wood Frog (Lithobates Sylvaticus) and the Bullfrog (Lithobates Catesbeianus)

Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide–capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination \u3e wood frogs alone \u3e bullfrogs in combination \u3e bullfrogs alone \u3e controls. In all gold-exposed groups of tadpoles, gold was concentrated in the anterior region compared with the posterior region of the body. The concentration of gold nanoparticles in the anterior region of wood frogs both alone and in combination with bullfrogs was significantly higher than the corresponding posterior regions. We also measured depuration time of gold in wood frogs. After 21 d in a solution of gold nanoparticles, tadpoles lost \u3e83% of internalized gold when placed in gold-free water for 5 d. After 10 d in gold-free water, tadpoles lost 94% of their gold. After 15 d, gold concentrations were below the level of detection. Our finding of differential uptake between closely related species living in similar habitats with overlapping geographical distributions argues against generalizing toxicological effects of nanoparticles for a large group of organisms based on measurements in only one species

Provenance and Paleogeography of the 25-17 Ma Rainbow Gardens Formation: Evidence for Tectonic Activity at Ca. 19 Ma and Internal Drainage rather than Throughgoing Paleorivers on the Southwestern Colorado Plateau

The paleogeographic evolution of the Lake Mead region of southern Nevada and northwest Arizona is crucial to understanding the geologic history of the U.S. Southwest, including the evolution of the Colorado Plateau and formation of the Grand Canyon. The ca. 25–17 Ma Rainbow Gardens Formation in the Lake Mead region, the informally named, roughly coeval Jean Conglomerate, and the ca. 24–19 Ma Buck and Doe Conglomerate southeast of Lake Mead hold the only stratigraphic evidence for the Cenozoic pre-extensional geology and paleogeography of this area. Building on prior work, we present new sedimentologic and stratigraphic data, including sandstone provenance and detrital zircon data, to create a more detailed paleogeographic picture of the Lake Mead, Grand Wash Trough, and Hualapai Plateau region from 25 to 18 Ma. These data confirm that sediment was sourced primarily from Paleozoic strata exposed in surrounding Sevier and Laramide uplifts and active volcanic fields to the north. In addition, a distinctive signal of coarse sediment derived from Proterozoic crystalline basement first appeared in the southwestern corner of the basin ca. 25 Ma at the beginning of Rainbow Gardens Formation deposition and then prograded north and east ca. 19 Ma across the southern half of the basin. Regional thermochronologic data suggest that Cretaceous deposits likely blanketed the Lake Mead region by the end of Sevier thrusting. Post-Laramide northward cliff retreat off the Kingman/Mogollon uplifts left a stepped erosion surface with progressively younger strata preserved northward, on which Rainbow Gardens Formation strata were deposited. Deposition of the Rainbow Gardens Formation in general and the 19 Ma progradational pulse in particular may reflect tectonic uplift events just prior to onset of rapid extension at 17 Ma, as supported by both thermochronology and sedimentary data. Data presented here negate the California and Arizona River hypotheses for an “old” Grand Canyon and also negate models wherein the Rainbow Gardens Formation was the depocenter for a 25–18 Ma Little Colorado paleoriver flowing west through East Kaibab paleocanyons. Instead, provenance and paleocurrent data suggest local to regional sources for deposition of the Rainbow Gardens Formation atop a stripped low-relief western Colorado Plateau surface and preclude any significant input from a regional throughgoing paleoriver entering the basin from the east or northeast

Design of Refractory Metal Heat Pipe Life Test Environment Chamber, Cooling System, and Radio Frequency Heating System

A series of 16 Mo-44.5%Re alloy/sodium heat pipes will be experimentally tested to examine heat pipe aging. To support this evaluation, an environmental test chamber and a number of auxiliary subsystems are required. These subsystems include radio frequency (RF) power supplies/inductive coils, recirculation water coolant loops, and chamber gas conditioning. The heat pipes will be grouped, based on like power and gas mixture requirements, into three clusters of five units each, configured in a pentagonal arrangement. The highest powered heat pipe will be tested separately. Test chamber atmospheric purity is targeted at <0.3 ppb oxygen at an approximate operating pressure of 76 torr (.1.5 psia), maintained by active purification (oxygen level is comparable to a 10(exp -6) torr environment). Treated water will be used in two independent cooling circuits to remove .85 kW. One circuit will service the RF hardware while the other will maintain the heat pipe calorimetry. Initial procedures for the startup and operation of support systems have been identified. Each of these subsystems is outfitted with a variety of instrumentation, integrated with distributed real-time controllers and computers. A local area network provides communication between all devices. This data and control network continuously monitors the health of the test hardware, providing warning indicators followed by automatic shutdown should potentially damaging conditions develop. During hardware construction, a number of checkout tests.many making use of stainless steel prototype heat pipes that are already fabricated.will be required to verify operation

African Food Security Fellows’ Perceptions of Their Experiences in the United States: Reflective Journaling as a Way to Interpret and Understand an International Experience

The study reports on a reciprocal exchange program funded by the U.S. Department of State. It involved 14 Food Security Fellows, including seven each from Kenya and Uganda, who were community leaders, policymakers, and media professionals. The Fellows experienced afive-week training program on issues of food securityand the unique role improved communication networks could play in reducing food insufficiency in their countries. During their exchange, the Fellows were asked to keep reflective journals chronicling their training experiences and interactions with Americans and their culture. The journal entries were transcribedandcoded, and emergent themeswere identified in concert with the study’s purpose and research questions. Established procedures to address researcher reflexivity and enabletransferability of the findings were followed. The data analysis yielded 41 codes from which 11 themeswere derived. The Fellows expressed a more positive attitude about Americans and the United States at the program’s end. They also described an appreciation for the role of youth development in agriculture and the need for extension educators,researchers, and university personnelto work together to ensure a nation’s food security. Future exchanges should provide participants with an internship experience instead of only job shadowing opportunitie